1. Field of the Invention
This invention relates to the production of shredded potato food products and to the products obtained thereby.
2. Description of the Prior Art
In the production of a cracker or biscuit from potato flour "checking" or the formation of hairline cracks due to water migration during and subsequent to baking is an acute problem. While checking is a problem common to the production of biscuits based upon cereal grains, such as wheat, rice, corn and the like, the phenomenon occurs to a greater extent in attempting to produce a biscuit from a potato dough. Potato doughs tend to form a more brittle product upon baking than do other doughs. Accordingly, hairline cracks due to checking have a greater tendency to propagate and result in a broken product.
The shredding process however, incorporates an open or webbed configuration into the product. The large surface area resulting from the production of shreds permits easier escape of water. Additionally, the escape of water from the product is more uniform. It is, accordingly, less stressful and does not lend itself to checking.
The moisture content of raw potatoes is too high for shredding. Potatoes typically have a moisture content of from about 70% to about 80% by weight, based upon the weight of the potato. In attempting to shred raw potatoes, long continuous shreds cannot be obtained. The potatoes become mushy upon shredding. Cooking of the whole potato does not substantially reduce the moisture content of the potato and does not impart a consistency to it which would enable the continuous production of shreds.
Several processes are known for the production of ready-to-eat breakfast cereals which are in shredded form. Cereal grains, however, as opposed to potatoes are of a size which is suitable for shredding. In conventional processes for producing shredded cereals, the grain is cooked and then permitted to temper to increase shred strength. Tempering of the cooked grains prior to shredding has generally been considered necessary for obtaining strong, continuous shreds. In U.S. Pat. Nos. 548,086 and 1,159,045, cooked wheat or similar grains are subjected to tempering times of over 12 hours before shredding. As described in U.S. Pat. No. 4,179,527, in the manufacture of a whole wheat food product such as shredded wheat, whole wheat is cooked sufficiently to gelatinize the starch. Gelatinization is a function of water penetration into the whole berry, temperature, and time, for a given type of grain. According to U.S. Pat. No. 4,179,527, the gelatinization of wheat starch involves a destruction of bonds in the crystalline regions of starch granules. Retrogradation is the return of the starch molecules to a crystalline structure, which is different from the original crystalline structures, upon cooling. Tempering permits the gelatinized wheat starch to slowly cool and permits water migration through the wheat particles to achieve a uniform water distribution within the particles. Retrogradation occurs during tempering. As reported in U.S. Pat. No. 4,179,527, if shredding is attempted shortly after cooking, the insufficient degree of retrogradation or tempering results in at best, short noncontinuous strands and/or strands which are tough, curly, or suffer from other physical or textural disadvantage. In U.S. Pat. No. 4,179,527, the time required for the tempering of cooked whole wheat is substantially reduced by chilling the wheat at a temperature of from 1.degree. C. to about 12.degree. C.
Numerous other processes for producing shredded cereal products with reduced tempering times or without any apparent tempering are also known. Shredded cereal products, whether tempering is used or not, have also been produced by shredding the cereal in a form other than its cooked berry form.
Processes wherein tempering is not specifically mentioned or is indicated as being optional in the production of cereals from wheat or other grains, are disclosed in U.S. Pat. Nos. 1,189,130, 2,008,024, 1,946,803, 502,378, 897,181, 3,062,657, 3,462,277, 3,732,109 and Canadian Pat. No. 674,046.
In U.S. Pat. No. 1,189,130, thoroughly moistened bran, such as wheat bran, is mixed with up to 50% of whole wheat or other gelatinous cereal flour or starch-bearing material, and is cooked in pans in a steam retort. The cooked product is dried to a lumpy condition, the lumps are pressed through a vial mesh and the resulting rice sized lumps are then fed through shredding mills.
In U.S. Pat. No. 2,008,024, a cereal biscuit is prepared by steaming or boiling wheat alone or with other forms of cereal or food material, surface drying the cooked product, and then converting it into a thin ribbed sheet. The shredding rolls are spaced sufficiently apart so that a sheeted material with ribs is obtained instead of a shredded product.
In U.S. Pat. No. 1,946,803, rice, alone or in combination with bran, is steam cooked, dried and cooled to a rubbery consistency, ground and optionally tempered to effect a uniform water distribution. This product is then passed between grooved rollers to form long flat ribbons. These ribbons are dried to produce a brittle product which is broken and then puffed by toasting.
In U.S. Pat. No. 502,378, a cereal grain is prepared for shredding by boiling, steaming, steeping or soaking. Depending upon the spacing between the rollers, a product in the form of threads, lace, ribbons, or sheets, and the like, is obtained.
In U.S. Pat. No. 897,181, cereal grain or vegetable in whole form is wetted but not cooked and then passed repeatedly between grooved rollers and then baked. Boiling or steaming of the grain or vegetable, it is disclosed, produces considerable change in its chemical quality and a number of the nutritious soluble elements escapes to the water.
In the processes of the remaining four patents, a shredded product is not produced by means of shredding rolls. In U.S. Pat. No. 3,062,657, flour and water are mixed to form a dough in an extruder. The dough is cooked in the extruder and then tempered in the extruder at a lower temperature. The extrudates are cut into pellets to simulate cooked and dried grains such as corn grits, whole wheat berries, oat groats, rice and the like. The extrudates, it is disclosed, have a moisture content ideal for flaking. It is generally on the order of 18 to 24% by weight, the moisture being uniformly distributed throughout so that the necessity for tempering is entirely eliminated and the extrudate can be immediately transferred to a flaking operation. It is disclosed that it is preferable to further cool the extrudate before it enters the flaking device to optimize flaking properties.
In U.S. Pat. No. 3,462,277, a mixture of cereal flour or grits and water is passed through an extruder to gelatinize the starch while the dough is cooked and transformed into a rubber-like mass. The moisture content of the mixture is 13 to 35%. The continuous U-shaped extrudate is pinched off into segments by cutting rolls to form canoe-shaped cereal products. The separated canoe-shaped pieces are then dried to below 15% moisture.
U.S. Pat. No. 3,732,109, discloses the production of a ready-to-eat oat cereal biscuit by subjecting an oat flour-water mixture to a water boiling temperature and superatmospheric pressure to gelatinize a portion of the starch in the oat flour. The mixture then passes through an orifice and the extruded product is cut into small pieces. The flake-shaped pieces which are formed are dried to a moisture content of from about 2% to about 6% by weight water. The dried flakes are then subdivided, admixed with a syrup, and compacted into the form of a biscuit. The formed biscuits are then dried to a moisture content of from about 4 to 5% by weight.
In Canadian Pat. No. 674,046, a shredded dry oat cereal product is produced without the use of shredding rolls. A dough is cooked in a screw extruder, extruded through orifices to form a strand bundle, and the strand bundle is cut into pieces by a cutting device which may be a pair of rolls.
Processes for the production of shredded cereals from cereal grains wherein considerable tempering is used, as in the conventional process for the production of shredded wheat, are disclosed in U.S. Pat. Nos. 1,159,045, 1,170,162, 1,197,297, and 4,004,035. In U.S. Pat. Nos. 1,159,045, 1,170,162 and 1,197,297, the whole berry is pulverized so as to permit flavoring ingredients to be incorporated in the final product. A dough is formed from flour, flavoring, and water. The dough is then cooked, rolled into slabs and then atmospherically dried for a period of 24 to 40 hours. The dried product is toasted, broken into pea size pieces, dried and then shredded. In U.S. Pat. No. 4,004,035, it is disclosed that during the continuous production of shredded biscuits using a press type cutter or rotating contact cutter, to sever the web across the shreds, the tensile strength and stickiness of the shredded material limits the ability of these cutting devices to perform satisfactorily. The shredded material, it is disclosed, tends to adhere to the blade or the blade will not completely sever it. In U.S. Pat. No. 4,004,035, the shredded biscuits are formed by depositing a layer of shredded cereal in zig-zag configuration on a moving belt and then severing the material. In addition to whole wheat, other foods capable of being shredded, such as other cooked cereal, wheat germ, defatted soy, other vegetable protein, fruits, vegetable slurries and mixtures thereof may be employed in producing the biscuits. The food is softened by cooking and tempering prior to shredding.
In the production of shredded cereals by means of shredding rolls, obtaining the cooked cereal in a form which will produce continuous shreds is only one of several problems which are encountered.
Cooking to eliminate white centers in grains is taught in U.S. Pat. No. 2,421,216. Particles of cereal grains such as corn, rye, wheat, bran, rice, or oat groats are composited with particles of de-fatted soya beans in the form of grits, flakes, or meal to enhance the protein content of the cereal by use of a two-stage pressure cooking step.
The total cooking period to which the cereal component is subjected to should, according to U.S. Pat. No. 2,421,216, be such that the starches are hydrolyzed and highly dextrinized and the particles superficially gelatinized with no free starch or white center. The cereal particles, it is taught, should also have a light adhesive action of the intermediately added soya bean particles. The mixed mass of cereal and soys which is removed from the cooker, has a moisture content from about 30 to about 45%. This mass is then dried to a moisture content of from about 24 to about 32% using air at about 130.degree. F. The dried mass is then tempered for about 15 to 30 minutes before shredding in a shredding mill wherein the particles of soya become substantially uniformly spread out over and mixed with the cereal particles and adhered thereto by pressure through the shredding rolls.
In U.S. Pat. No. 3,512,990 a dough, made from farinaceous materials such as wheat, corn, oats, rice, potatoes, or legumes, is optionally partially or completely cooked with added moisture, to an approximate moisture content of about 30%. After this cooking step, the mixture is rendered homogeneous by passing it through an extruder or a hammer mill, such as Fitzmill. The milled or extruded product is dried to an approximate moisture content of 22 to 24%. The dried dough is then compacted between two rolls to provide a shredding effect and produce a sheet of dough having diamond-like regularly spaced perforations. The sheet of dough is then severed into strips, folded to form small biscuits which are closed on three sides and then deep fried.
In U.S. Pat. Nos. 987,088, 1,019,831, and 1,021,473, corn or another grain is ground and immersed in an amount of water which is limited to that which will be taken up by the grain during cooking. The purpose of this is to preserve in the cooked article the aroma and other properties of the grain which might otherwise be carried off or dissipated by the evolution of steam or vapor. In these processes, the cooked dough is extruded through a perforated plate to obtain filaments.
In U.S. Pat. No. 4,310,560 particulate edible materials, including at least one material which acquires surface stickiness when moistened and a chemical leavening system are contacted with a spray of water and formed into pellets on a pelletizing disk. The edible material may include starches, such as those derived from wheat, corn, rice, potatoes, tapioca, and the like, including pregelatinized starches. The pellets are heated to a temperature sufficient to effect reaction of the leavening system to release carbon dioxide to provide the pellets with a porous cellular structure.
However, in the production of shredded potato products, heating or cooking of the potatoe starch in the presence of water prior to shredding leads to the formation of gel-like or rubbery material and tacky substances which hampers the continous production of discrete potato particulates or dough pieces. High shear mixing of a potato starch source and water generates heat which overgelatinizes potato starch and forms a well-worked dough which is difficult to form into particulates. Shredded potato products made from such a dough tend to delaminate subsequent to or during cooking. Additionally, unless the dough pieces are tempered to distribute the water substantially uniformly throughout the dough pieces, the dough pieces will tend to accumulate at the feed hoppers and shredding rolls after several hours of operation inhibiting a continuous process.
The present invention provides a process for the production of ready-to-eat shredded potato products made from potatoes alone, or in combination with at least one cereal grain, which have a pleasant mouthfeel, have a substantially uniform off-white to golden tan color, have a pleasant potato taste, and which do not delaminate. Potato particulates or dough pieces are produced in the form of discrete, individual or non-interconnected particles which have good flowability through material handling equipment, do not stick to or accumulate in hoppers or on the shredding rolls, and are readily shreddable into strong continuous shreds on a consistent basis.